Such systems in which a container having workpieces (usually arranged randomly) is emptied in an automated fashion, for example by use of a robot, have become known under the name “bin picking” In this process, the workpieces arranged in the container are detected by the object recognition device and the gripper is controlled using the data on the detected workpieces such that it picks the workpieces and removes them individually from the container.
Most apparatus for “bin picking”, however, have previously not moved past an experimental stage since a variety of problems have to be overcome in the process security, process speed and accuracy.
It is therefore the object of the present invention to provide an apparatus for the automated removal of workpieces arranged in a container which has improved properties with respect to process security, speed and/or accuracy.
This object is achieved in accordance with the invention by an apparatus for the automated removal of workpieces arranged in a container, comprising a first object recognition device for detecting the workpieces and a first gripper for picking and removing the workpieces from the container; and a control for evaluating the data of the first object recognition device, for path planning and for controlling the first gripper, characterized by an intermediate station on which the first gripper places the workpieces after the removal from the container and a positioning apparatus which positions the work pieces more accurately and/or singularizes the workpieces starting from the intermediate station.
Preferred embodiments of the invention form the subject of the dependent claims.
The present invention relates to an apparatus for the automated removal of workpieces arranged in a container, comprising a first object recognition device for detecting the workpieces and a first gripper for picking and removing the workpieces from the container and a control for evaluating the data of the first object recognition device, for track planning and for controlling the first gripper. The control can in this respect in particular comprise an evaluation device for evaluating the data, a track planning module for track planning and a control unit for controlling the gripper. In accordance with the invention, an intermediate station is provided in this respect on which the first gripper places the workpieces after the removal from the container and a positioning apparatus is provided which positions the work pieces more accurately and/or singularizes the workpieces starting from the intermediate station.
The first gripper does not yet have to pick or place the workpieces with the final accuracy required for the further processing of the workpieces thanks to the use of an intermediate station in accordance with the invention, which substantially simplifies the emptying of the container and increases process times. Furthermore, on an emptying of the workpieces from the container, it also does not have to be ensured that the workpieces are singularized completely and reliably. The intermediate station is rather used in accordance with the invention to position the workpieces more accurately and optionally finally to singularize them.
The apparatus in accordance with the invention can in this respect in particular serve the removal of workpieces arranged randomly in the container since the position of the workpieces can be determined by a suitable object recognition device and therefore does not have to be known in advance. The apparatus can naturally, however, also be used when the workpieces are already present with a certain order in the container.
The apparatus in accordance with the invention can in this respect in particular serve the automated arrangement of the workpieces at a target receiver, with the control controlling the positioning apparatus such that the workpieces are arranged, starting from the intermediate station at the target receiver with a greater accuracy than they were placed on the intermediate station.
The inventors of the present invention have recognized in this respect that the process security, accuracy and speed required in industrial applications can only be reached by the use of such an intermediate station.
In accordance with the invention, in this respect, any desired gripper, in particular a mechanical, magnetic and/or pneumatic gripper, can be used as the first gripper for picking the workpieces in the container.
A magnetic and/or pneumatic gripper is, however, particularly preferably used as the first gripper for picking the workpiece in the container. Such magnetic and/or pneumatic grippers can in this respect in particular also be used in the handling of workpieces having a position-orientated gripping zone and/or an asymmetrical contour as well as with workpieces without any specific gripping zone such as with metal sheets. They can, however, naturally also be used with symmetrical workpieces, for example with rotationally symmetrical workpieces.
Magnetic and/or pneumatic grippers have the advantage that they have to be positioned less exactly toward the workpiece in order to be able to pick it. Such grippers in particular also allow a certain offset between the workpiece and the gripper or they allow picking at a plurality of different points of a workpiece.
In this respect, a magnetic gripper is particularly preferably used for picking the workpiece from the container.
The gripper in accordance with the invention can furthermore be arranged cropped at the end member of a gripping arm. It is possible by the cropped configuration of the gripper also to use it directly next to a side wall of the container in the interior of the container for picking workpieces. It is thus in particular avoided that interfering edges further up at the gripping arm prevent a moving of the magnetic gripper directly to a wall region of the container.
In accordance with the invention, any desired system which allows the identification of the workpieces and the selection of a workpiece suitable for picking can be used as an object recognition device for detecting the workpieces.
If the position of the workpieces in the container is known in advance, for example because they are arranged in order in the container, the object recognition device can optionally also only take place using such already known positional data.
The detection of the workpieces, however, advantageously comprises a data logging by a measurement process. An identification of the individual workpieces in the detection zone from which a workpiece suitable for picking is selected then takes place by evaluation of the data. The movement of the gripper or of the gripping arm moving it is planned on the basis of the positional data of this workpiece. In this respect, a collision check can be carried out so that a movement routine is selected in which the gripper or the gripping arm does not collide with interfering edges such as the other workpieces and/or the side walls of the container. The gripper or the gripping arm is then controlled using the data thus calculated.
In this respect, in particular optical sensors are used as the object recognition device, with in particular laser sensors and/or image sensors being able to be used. The sensors can in this respect work two-dimensionally, two-and-half-dimensionally and three-dimensionally. A 3D laser scanner is particularly preferably used in this respect.
The first object recognition device for detecting the workpieces in the container is in this respect preferably arranged in its measurement position above the container.
In the selection of the workpiece to be picked, it can in particular be detected in this respect whether a workpiece was identified which can be picked with a predefined first relative position between the workpiece and the gripper.
Such a first relative position can in particular represent an ideal picking position between the workpiece and the gripper which comprises the fact with a magnetic gripper, for example, that the magnetic surface of the gripper overlaps ideally with the workpiece.
However, the case can arise with parts not lying on one another in order than none of the workpieces present in the container can be picked with such a first relative position. In accordance with the invention, the control can in this case select a workpiece which is picked with a second picking position, for example a not ideal picking position. With a magnetic gripper, for example, a certain offset can be allowed in this respect between the ideal magnetic gripping surface and the workpiece. A picking position rotated by an angle with respect to the ideal magnetic picking position can likewise be considered as an alternative picking position with the magnetic gripper, for example having an angle offset of 90°. Alternatively, or also when this is not possible, a picking can be attempted at the highest point of the workpiece, for example. A plurality of alternative picking positions can in particular be provided which are used in the selection of the workpiece to be picked.
Provision can alternatively or additionally be made that the gripper is controlled in accordance with the invention such that for the case it cannot pick up a workpiece with a first position calculated for picking, it repeats the picking with a second, changed position. This is only possible with mechanical grippers if the workpiece provides a plurality of gripping zones. With magnetic and/or pneumatic grippers, in contrast, picking can also takes place more easily with a certain offset from an ideal picking position.
In an advantageous embodiment of the present invention, the positioning apparatus also comprises a gripper for picking the workpieces off from the intermediate station.
In a first variant, this gripper can in the respect be the first gripper which is thus used both for removing the workpieces from the container and for the more exact positioning of the workpiece starting from the intermediate station.
In a first preferred variant, the gripper of the positioning apparatus is, however, a second, separate gripper.
In this respect, in turn, any desired gripper can be used as the second gripper, in particular a mechanical, magnetic and/or pneumatic gripper. The second gripper in this respect preferably has a different design than the first gripper.
The present invention thus comprises all combinations of first and second grippers and in particular the combinations of magnetic/mechanical, mechanical/mechanical, pneumatic/mechanical, mechanical/pneumatic, pneumatic/pneumatic and magnetic/pneumatic.
The second gripper of the positioning apparatus is, however, particularly advantageously a mechanical gripper. Such a mechanical gripper has a higher accuracy in the picking and positioning of the workpiece, but also requires a more accurate delivery to the workpiece. In this respect, such a mechanical gripper having sufficient process security and accuracy can be used through the intermediate station in accordance with the invention on which the workpieces are already presingularized and prepositioned.
The design of the mechanical gripper in this respect accordingly depends on the workpieces to be picked. For example, the mechanical gripper can be a finger gripper, in particular a multifinger gripper.
It is furthermore conceivable to use a magnetic gripper having a plurality of magnetic gripping zones, which magnetic gripper accordingly allows a more accurate picking The gripping zones are in this respect advantageously matched to the workpiece to be picked.
The present invention in this respect allows a one hundred percent emptying the container in a preferred variant. This is in particular achieved by the use of an intermediate station in accordance with the invention and/or by the use of a magnetic and/or pneumatic gripper for picking the workpieces in the container.
The present invention thus ensures that all the workpieces present in a container can actually also be removed, which would not be possible in many cases with a direct arrangement of the workpieces at a target receiver and/or on the use of a mechanical gripper for removing the workpieces from the container.
In this respect, after the removal of a workpiece identified as the last workpiece in the container by the controller, a detection of workpieces in the container can advantageously take place again to ensure that the container has also actually been completely emptied. A channeling out of the container advantageously only takes place when no workpieces were able to be identified in this detection.
The present invention preferably comprises a second object recognition device for detecting the workpieces on the intermediate station. The workpieces placed on the intermediate station are thus detected again in accordance with the invention and can thus be picked and/or singularized with increased accuracy by the positioning apparatus, and in particular by the gripper of the positioning apparatus.
In this respect, an object recognition device can be used as an object recognition device for detecting the workpieces such as has already been described above with respect to the first object recognition device for detecting the workpieces in the container.
The evaluation of the data, identification and selection of the workpieces, the track planning and the control of the gripper of the positioning apparatus can also take place in a similar manner as has been represented above with respect to the corresponding steps on picking from the container.
Furthermore, a check can take place in the control whether the workpieces are the workpieces desired for the further processing or a workpiece arranged in the container by error. A comparison of workpiece data which were determined by evaluating the data of the object recognition device can in particular take place in this respect with predefined demands.
If an erroneous workpiece is recognized, the control sorts it out by a corresponding control of the gripper.
The sorting out of workpieces in this respect advantageously takes place on the intermediate station, in particular by evaluating the data of the second object recognition device and by controlling the second gripper and/or via a channeling out of the transport belt, for example when the gripper cannot pick the erroneous part.
Provision can furthermore be made that the detection of the workpieces on the intermediate station takes place with a higher accuracy than the detection of the workpieces in the container, for example with a higher resolution.
The second object recognition device for detecting the workpieces on the intermediate station is in this respect advantageously arranged in or above a removal region of the intermediate station. The second object recognition device can in particular thus detect the workpieces which should be picked by the positioning apparatus in the removal region of the intermediate station.
As already initially explained, it is not necessary through the use of the intermediate station to position the workpieces exactly on the placing on the intermediate station since the further positioning takes place by the positioning apparatus. The work pieces can in this respect in particular be randomly placed on the intermediate station.
The workpieces can in this respect in particular be arranged randomly on the intermediate station and can be picked by the positioning apparatus and then positioned and/or singularized.
Provision can be made in this respect that the control controls the first gripper for placing the workpieces on the intermediate station such that the workpieces fall onto a placing region from a certain height. This procedure has a plurality of advantages:
On the one hand, it is thus prevented that the gripper with the workpiece collides with the intermediate station on the placing of the workpieces since the workpieces still have a certain distance from the intermediate station on being dropped. The position of the workpiece at the gripper furthermore does not have to be known. In addition, an exact positioning can be dispensed with, which increases the speed. This procedure furthermore has the advantage with workpieces which can catch with one another that they release from one another when falling onto the placing region. In addition, this dropping allows a separation of a plurality of workpieces picked up simultaneously.
The dropping of the workpieces has special advantages in this respect when a magnetic and/or pneumatic gripper is used for removing the workpieces from the container. In this case, the position of the workpiece at the gripper is namely not necessarily clearly defined so that a positioning of the workpieces on the intermediate station would hardly be possible. Furthermore, in particular with magnetic grippers, it can never be precluded that a plurality of workpieces are picked up so that the dropping results in a further singularization.
The placing region of the intermediate zone advantageously comprises a slanted plane in this respect. The workpieces are in particular dropped onto the slanted plane in this respect. The slanted plane in this respect serves the singularization and/or preorientation of the workpieces and/or the further transport of the workpieces. The slanted plane in this respect in particular serves as a slide for the workpieces.
The placing region configured as the slanted plane in this respect preferably has lateral abutment regions which guide the workpieces laterally. The abutment regions in this respect preferably narrow the slanted plane toward the bottom so that the workpieces are dropped in a relatively large region in the lateral direction and are nevertheless led through the narrowing abutment regions to a further transport region shorter in the lateral direction.
A height sensor is preferably provided for recognizing the distance of a workpiece arranged at the gripper from the placing region in the vertical direction. The position of the workpiece at the gripper hereby does not have to be known to drop the workpiece from a predefined height. This height can rather be recognized by the height sensor. The height sensor in this respect in particular serves the recognition of the height of the workpiece above the slanted plane.
In a preferred embodiment, a light barrier arrangement arranged laterally at the placing region is used as a vertical sensor. A workpiece can in this respect in particular be dropped when it reaches the region monitored by the light barrier arrangement.
The first gripper is thus advantageously controlled so that it moves a workpiece removed from the container over the placing region of the intermediate station and lowers it there until the height sensor recognizes a predefined distance between the workpiece and the placing region. The workpiece is thereupon dropped.
In a particularly simple embodiment of the present invention, the placing region and the removal region of the intermediate station can be identical. The intermediate station in this case, for example, only comprises a surface on which the workpieces are placed and from which they are picked up again.
Provision can be made in a further embodiment that the placing region has, as described above, a slanted plane on which the workpieces slide up to the removal region.
The intermediate station, however, preferably comprises a transport device for the further transport of the workpieces away from a placing region. The transport device can have a drive in this respect. A transport belt can in particular be used in this respect.
Since the workpieces can be randomly arranged on the transport belt, the transport device advantageously has no receivers for the workpieces. The workpieces can in this respect in particular be randomly arranged on a transport surface, for example on a transport surface formed by a transport belt.
The transport device advantageously transports the workpieces from the placing region to a removal region in which the workpieces are picked by a gripper of the positioning apparatus and are taken from the intermediate station. The workpieces are advantageously detected by a second object recognition device before or in this removal region.
In this respect, the detection of the workpieces and/or the taking away of the workpieces advantageously takes place while the workpieces are located on the transport device. In this respect, the transport device is preferably stopped to detect and/or take off the workpieces. If a further workpiece is taken off, the transport device is moved on until the next workpiece was moved into the detection and/or removal region.
In this respect, data of the second object recognition device and/or a light barrier is/are used for controlling the transport belt.
In accordance with the invention, the workpieces falling onto the slanted plane slide to a first end of the transport device from where they are transported on the transport device to a removal region.
In accordance with the invention, the transport device can be equipped with a mechanical reorientation device which at least partly changes the position of workpieces on the transport from the placing region to the removal region and/or carries out a rough prepositioning.
Such a reorientation device is always of advantage when the workpieces cannot be picked by the positioning apparatus in certain positions. This can be the case, for example, when the workpieces come to lie on the transport apparatus on their narrow side, but can only be picked when they lie on their broad side. In this case, the reorientation device can be configured so that it throws over workpieces lying on their narrow sides.
In particular a flap and/or a bar can be provided as a reorientation device, said bar advantageously running transversely to the transport direction over the transport device. The flap or the bar is in this respect in particular arranged at a predefined height above the transport belt.
The intermediate placement element can thus in particular have a placing region and a removal region as well as a transport device which transports the workpieces from the placing region to the removal region. An object detection device can furthermore be arranged above the removal region. The transport from the loading side to the unloading side can in this respect be implemented in a variety of manners.
It is conceivable, for example, to use a transport device without a drive in which transport device the workpieces move from the placing region to the removal region solely due to gravity. A slanted plane can in particular be used in this respect on which the workpieces slide down.
The transport device, however, as described above, preferably has a drive. In this respect, different configurations are conceivable:
The drive can thus take place in linear manner via a transport belt, for example, or e.g. via a pusher, a shuttle or a slide. A motor or a linear drive such as a pneumatic cylinder can be used as the drive in this respect.
A circular embodiment of the transport device is furthermore conceivable. For example, a turntable can thus be provided on which the workpieces are placed down at one side and are transported to the other side by rotating the table. In this respect, e.g. a round, segmented table and/or a circular store can be used. It is likewise conceivable to use a loop or a circular transport belt.
The transport can furthermore also take place in the vertical direction, in particular between a plurality of planes lying above one another. In this respect, the transport can take place from top to bottom and/or from bottom to top.
It is furthermore conceivable to use a combination of the above-named possibilities as the transport device.
The position of the workpiece is preferably changed during the transport to increase the removal accuracy (place down inaccurately, remove accurately). This can take place, for example, by the above-described reorientation device, in particular by end abutments, guide rails with a chamfer, spring mechanisms, etc. The intermediate station can furthermore also be used as a transfer picking site.
In a possible embodiment, the transport device can in this respect be configured as a transport surface which is traveled via a linear drive such as a transport cylinder from the placing region to the removal region and back again. In this respect, two such transport surfaces are particularly preferably provided so that an empty transport surface is always available for loading in the placing region and a filled transport surface in the removal region for unloading. The system can hereby work without waiting times. The linear drives of the two transport surfaces can in this respect in particular be arranged in parallel with one another.
In accordance with the invention, the intermediate station can be equipped with an occupation sensor to detect the occupation of the placing region and/or of the transport device and/or of the removal region. In this respect, in particular a light barrier can be used as the occupation sensor, with the light barrier advantageously being arranged to the side at the placing region and/or at the transport device and/or at the removal region. The light barrier is in this respect in particular arranged at a certain height and recognizes whether a plurality of workpieces are stacked above one another on the transport device.
The control is in this respect advantageously configured so that the placing down of workpieces on the intermediate station is stopped when too high an occupation is recognized. The occupation sensor in this respect is in particular used to monitor the occupation of that part of the transport device into which the workpieces slide from the placement region. If this region is loaded too much, the placing down of workpieces onto the intermediate station is stopped until there is again sufficient room in this region by the removal of workpieces by the positioning apparatus and the further movement of the transport device.
In accordance with the invention, the first gripper and/or the second gripper can be moved via automatically controlled adjustment axes of a gripping arm.
In a first embodiment variant, the first gripper and the second gripper can in this respect be arranged at a common gripping arm and can be moved via it.
The first and second grippers are, however, preferably arranged at separate gripping arms and can thus be moved independently of one another.
The gripping arm or gripping arms can in particular be the robot arm of a six-axial industrial robot. Alternatively, however, a gripping arm arranged at an areal or linear portal can also be used which optionally has at least one further axis of rotation.
Furthermore, the container with the workpieces could also be moved to generate at least some of the relative movement between the workpiece and the first gripper.
The present invention furthermore includes a method for the automatic removal of workpieces arranged in a container. The method in this respect can include the steps                detecting the workpieces;        picking at least one workpiece using a first gripper; and        removing the workpiece from the container.        
Provision is made in accordance with the invention that, after the removal from the container, the workpieces are placed onto an intermediate station from where the workpieces are positioned more accurately and/or are singularized by at least one further positioning step.
The method in accordance with the invention in this respect preferably takes place as was already described above with regard to the apparatus. The method in accordance with the invention particularly preferably takes place in this respect using an apparatus as was presented above.
The present invention furthermore comprises a computer program for carrying out a method in accordance with the invention. The computer program in particular comprises commands which implement a method in accordance with the invention on an apparatus for the automated removal of workpieces randomly arranged in a container. The computer program in accordance with the invention in particular serves the implementation of a control for an apparatus as described above in this respect.
All the steps in the handling of the workpieces advantageously take place by the method in accordance with the invention and/or by the apparatus in accordance with the invention in a fully automated manner and without a user intervention being necessary.